JP5435688B2 - Substrate processing apparatus and substrate processing method - Google Patents

Description

  The present invention relates to a substrate processing apparatus and a substrate processing method, and more particularly to a substrate processing apparatus and a substrate processing method capable of cleaning a substrate such as a semiconductor substrate or a liquid crystal substrate.

In a substrate processing apparatus, a chemical solution in which sulfuric acid (H ₂ SO ₄ ) and hydrogen peroxide water (H ₂ O ₂ ) are mixed in order to remove a resist from a substrate in a manufacturing process of a substrate such as a semiconductor wafer or a liquid crystal substrate. The used resist is stripped (see Patent Document 1).
JP 2006-278509 A

  However, in Patent Document 1, since activated oxygen is required for resist destruction, hydrogen peroxide is used. However, when sulfuric acid and hydrogen peroxide are mixed, water is generated in the reaction process. In addition, the concentration of sulfuric acid gradually decreases. That is, since sulfuric acid is diluted, sulfuric acid cannot be reused, and a mixture of sulfuric acid and hydrogen peroxide water can be used only once. For this reason, processing cost becomes high and environmental load is large. Therefore, it is desired to prevent dilution of sulfuric acid by eliminating generation of water without using hydrogen peroxide.

  The present invention has been made in view of the above, and an object thereof is to prevent the resist stripping solution such as sulfuric acid from being diluted and to reuse the resist stripping solution so that the resist stripping can be efficiently performed. An object of the present invention is to provide a substrate processing apparatus and a substrate processing method.

The substrate processing apparatus of the present invention is a substrate processing apparatus that supplies sulfuric acid as a resist stripping solution to the surface of a substrate to strip the resist from the substrate, and contains ozone gas microbubbles in the resist stripping solution. A micro-bubble generating unit that generates a resist stripping solution containing the microbubbles, and a resist stripping solution that includes the microbubbles from the microbubble generating unit in the form of droplets on the surface of the substrate. When supplying a supply nozzle, a resist stripping solution containing microbubbles into droplets, ozone gas is supplied to the resist stripping solution containing microbubbles, and an ozone gas supply unit for supplying ozone gas to the surface of the substrate. the resist and piping stripping solution back into the microbubble generation unit, a pump provided in the middle the pipe, said after being supplied to the surface of the substrate A sensor for detecting the sulfuric acid concentration of the dying stripping solution, and a control unit for determining whether the stripping solution supplied to the surface of the substrate can be reused based on the detection result of the sensor; When it is determined that the stripping liquid after being supplied to the surface of the substrate can be reused based on the detection signal of the sensor, the control unit activates the pump and supplies it to the surface of the substrate. After that, the stripping solution is returned to the microbubble generating unit via the pipe .

The substrate processing method of the present invention is a substrate processing method for supplying a sulfuric acid as a resist stripping solution to the surface of a substrate and stripping the resist from the surface of the substrate, wherein ozone gas is contained in the sulfuric acid using a microbubble generating unit. A step of generating a resist stripping solution including the microbubbles by mixing the microbubbles, a step of supplying the resist stripping solution including the microbubbles into droplets using ozone gas, and supplying the substrate to the surface of the substrate; Detecting the sulfuric acid concentration of the resist stripping solution after being supplied to the surface of the substrate, and the resist after being supplied to the surface of the substrate based on the sulfuric acid concentration detected in the step of detecting the sulfuric acid concentration The step of determining whether or not the stripping solution is reusable, and the resist stripping after being supplied to the surface of the substrate when it is determined that the stripping solution is reusable in the determining step. And having a step of returning the liquid to the fine bubbles generated unit.

  According to the present invention, it is possible to provide a substrate processing apparatus and a substrate processing method capable of preventing a resist stripping solution such as sulfuric acid from being diluted, reusing the resist stripping solution, and efficiently performing resist stripping. Can do.

  Embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 shows a first preferred embodiment of the substrate processing apparatus of the present invention.

  A substrate processing apparatus 1 shown in FIG. 1 includes a cassette station 2 for a cassette, a robot 3, and a plurality of processing units 4 and 4.

  The substrate processing apparatus 1 is an apparatus that performs single-wafer processing, and the cassette station 2 has a plurality of cassettes 5 and 5, and each cassette 5 accommodates a plurality of substrates W. An example of the substrate is a semiconductor wafer substrate.

  The robot 3 is disposed between the cassette station 2 and the plurality of processing units 4 and 4. The robot 3 transports the substrate W accommodated in each cassette 5 to the processing unit 4 side. Further, the robot 3 transports the processed substrate W on the processing unit 4 side to another cassette 5 and returns it. Each processing unit 4 is used to peel off unnecessary resist on the substrate W by holding and rotating the substrate W and supplying a resist stripping solution containing microbubbles.

  FIG. 2 shows a configuration example of the processing unit 4 of the substrate processing apparatus 1 shown in FIG.

  The single wafer processing unit 4 shown in FIG. 2 is an example of a resist stripping device 10, a substrate holding unit 11, an operation unit 12, a fan 13 with a filter for downflow, a cup 14, and a supply unit. A supply nozzle 15 and a processing chamber 16 are provided.

  The substrate holding part 11 includes a disk base member 17, a rotating shaft 18, and a motor 19, and the substrate W is detachably fixed on the base member 17. A cup 14, a supply nozzle 15, a base member 17, and a rotating shaft 18 of a motor 19 are accommodated in the processing chamber 16. A base member 17 is fixed to the tip of the rotating shaft 18. The base member 17 can be continuously rotated in the R direction by the motor 19 operating according to a command from the control unit 20.

  The supply nozzle 15 shown in FIG. 2 is arranged above the substrate W, and the supply nozzle 15 operates in the Z direction (vertical direction) and the X direction (radius of the substrate W) when the operation unit 12 is operated according to a command from the control unit 20. Direction).

  Next, the resist stripping apparatus 10 shown in FIG. 2 will be described.

  The resist stripping apparatus 10 shown in FIG. 2 includes a microbubble generating unit 30, ozone gas supply units 32 and 53, a sulfuric acid supply unit 34, a first heater 51, a second heater 52, and the like.

  The microbubble generation unit 30 is connected to an ozone gas supply unit 32 via a pipe 31 </ b> B and a valve 31. The microbubble generating unit 30 is connected to the sulfuric acid supply unit 34 via a pipe 33 </ b> B and a valve 33. The ozone gas supply unit 32 is a gas supply unit for supplying ozone gas which is an example of an oxidizing gas. Similarly, the sulfuric acid supply unit 34 is a resist stripping solution supply unit for supplying sulfuric acid, which is an example of a resist stripping solution. The valves 31 and 33 are controlled to open and close according to a command from the control unit 20.

  The microbubble generating unit 30 shown in FIG. 2 generates a large number of microbubbles by passing the ozone gas supplied from the ozone gas supply unit 32 through, for example, a first porous filter, and the sulfuric acid supplied from the sulfuric acid supply unit 34 is used, for example. By passing through the second porous filter, a large number of generated microbubbles are mixed and contained in sulfuric acid. Thereby, the microbubble production | generation unit 30 can produce | generate the sulfuric acid 40 containing many microbubbles.

  The microbubble generating unit 30 shown in FIG. 2 is connected to the supply nozzle 15 through the first heater 51 via a pipe 46 and a valve 47. For this reason, after the valve 47 is opened by a command from the control unit 20, the sulfuric acid 40 including the microbubbles in the microbubble generating unit 30 is heated through the first heater 51 through the pipe 46 and the valve 47. , And sprayed from the supply nozzle 15 onto the substrate W.

As shown in FIG. 2, another ozone gas supply unit 53 is connected to the supply nozzle 15 through the second heater 52 via a pipe 54 and a valve 55. For this reason, when the valve 55 is opened by a command from the control unit 20, the ozone gas in the ozone gas supply unit 53 is heated through the second heater 52 through the pipe 54 and the valve 55, and then is supplied from the supply nozzle 15 to the substrate. It is jetted as droplets of W. The ozone gas supply units 32 and 53 are an example of an oxidizing gas supply unit.

  In this way, the first heater 51 heats the sulfuric acid 40 containing microbubbles, and the second heater 52 heats the ozone gas from the ozone gas supply unit 53, so that the ozone gas on the substrate W reacts efficiently. It can contribute to resist stripping and can improve resist stripping. In addition, the 1st heater 51 and the 2nd heater 52 can be set as needed.

  Further, as an example of an oxidizing gas used when microbubbles are included in sulfuric acid, the resist on the substrate W can be more effectively removed by using ozone gas. In addition, it can replace with ozone gas and nitrogen gas and air can also be used and the effect similar to ozone gas is acquired.

  As shown in FIG. 2, the pump 45 is connected between the microbubble generating unit 30 and the bottom of the processing chamber 16 via pipes 56 and 57. When the pump 45 is operated according to a command from the control unit 20, the used sulfuric acid 58 accumulated in the processing chamber 16 is returned to the microbubble generating unit 30 and used again for the resist removal work of the substrate W. Can do.

  A tank 65 and a valve 66 are further connected to the pipe 56 at the bottom of the processing chamber 16. The tank 65 has a light source 67, an optical sensor 68, and a liquid level sensor 69. The light from the light source 67 passes through the sulfuric acid in the tank 65 and is received by the optical sensor 68, thereby detecting the concentration of sulfuric acid. The control unit 20 determines whether the used sulfuric acid can be used again based on the detection result of the sulfuric acid concentration. When the used sulfuric acid can be used again, the control unit 20 operates the pump 45 to return the sulfuric acid to the microbubble generating unit 30, but when the sulfuric acid cannot be reused, the valve 66 is opened to supply sulfuric acid. The tank 70 is discharged.

  The cleaning water supply unit 19M can supply cleaning water to the substrate W. Since a liquid other than sulfuric acid such as washing water is used, a pipe 60 and a valve 61 for collecting drainage other than sulfuric acid are connected to the bottom of the processing chamber 16. The drainage other than sulfuric acid is cleaning water used when cleaning the substrate W, for example, and is collected in the tank 62. The cleaning water may be pure water, for example.

  FIG. 3 shows a configuration example of the microbubble generating unit 30 shown in FIG. The microbubble generation unit 30 includes a first porous filter 81 and a second porous filter 82.

The first porous filter 81 and the second porous filter 82 shown in FIG. 3 constitute a microbubble generation mechanism, and the first porous filter 81 is a porous film such as a polymer film. For example, it is composed of a crazing part 131 and a film part 132. Craze portion 131 is formed in the hole portion of the film portion 132 has a plurality of fibrils 133, between each fibril 133 is void 134. This void 134 is the first hole of the first porous filter 81.

  The ozone gas supply unit 32 can supply the ozone gas by pressurizing the first porous filter 81 via the flow rate regulator 120 and the regulator 121. The flow regulator 120 and the regulator 121 constitute the valve 31 shown in FIG.

When compressed gas is given along the arrow S direction in FIG. 3 with a pressure of, for example, 0.3 to 3.0 kg / cm 2, the compressed ozone gas passes through the voids 134 between the fibrils 133. Many microbubbles are generated.

  On the other hand, the second porous filter 82 is, for example, a nonwoven fabric disposed in close contact with the film portion 132 of the first porous filter 81. The sulfuric acid supply unit 34 can supply sulfuric acid to the second porous filter 82.

  The second porous filter 82 separates a large number of microbubbles of ozone gas from the void 134 between the fibrils 133 from the first porous filter 81, thereby discharging the microbubbles as they are without causing the coalescence of the microbubbles. Thus, it plays the role of producing sulfuric acid 40 containing microbubbles.

  Next, a resist stripping method by the resist stripping apparatus 10 in the processing unit 4 described above will be described.

  The ozone gas supply unit 32 shown in FIG. 2 supplies ozone gas to the microbubble generation unit 30, and the sulfuric acid supply unit 34 supplies sulfuric acid, which is an example of a resist stripping solution, to the microbubble generation unit 30.

As shown in FIG. 3, the microbubble generation unit 30 generates a large number of microbubbles by passing the ozone gas supplied from the ozone gas supply unit 32 through the first porous filter 81, and is supplied from the sulfuric acid supply unit 34. By passing sulfuric acid through the second porous filter 82, a large number of generated microbubbles are mixed and contained in the sulfuric acid. Supplying ozone gas that is compressed against the first porous filter 81, the ozone gas is passed through sewing voids 134 between the fibrils 133 crazing portion 131, a large number of micro-bubbles are generated. These microbubbles by separating from the film unit 132 with the second porous filter 82, it is possible to discharge the sulfuric acid remains microbubbles without occur uniting of microbubbles.

  Thereby, the microbubble production | generation unit 30 produces | generates the sulfuric acid 40 containing many microbubbles.

  The sulfuric acid 40 containing the microbubbles in the microbubble generating unit 30 shown in FIG. 2 is heated through the first heater 51 and then sprayed as droplets from the supply nozzle 15 onto the substrate W. Further, as shown in FIG. 2, another ozone gas supply unit 53 is supplied to the supply nozzle 15 through the second heater 52.

  In this way, the first heater 51 heats the sulfuric acid 40 containing microbubbles, and the second heater 52 heats the ozone gas from the ozone gas supply unit 53, so that the ozone gas on the substrate W reacts efficiently. It can contribute to resist stripping and can improve resist stripping. In addition, the 1st heater 51 and the 2nd heater 52 can be set as needed.

As shown in FIG. 2, after sulfuric acid 40 containing microbubbles is sprayed from the supply nozzle 15 onto the substrate W and the resist of the substrate W is removed, the used sulfuric acid drainage enters the tank 65 and enters the light source 67 and the light. When passing between the sensor 68 is detected concentration of sulfuric acid. Based on the detection result of the concentration of sulfuric acid, the control unit 20 determines whether or not sulfuric acid can be used again. If the sulfuric acid can be used again, the control unit 20 operates the pump 45 to supply sulfuric acid. When the sulfuric acid cannot be reused, the valve 66 is opened and the sulfuric acid is discharged into the tank 70.

  This makes it possible to reuse the sulfuric acid 40 containing microbubbles, prevent the resist stripping solution such as sulfuric acid from being diluted, and reuse the resist stripping solution, thereby efficiently performing the resist stripping process. it can. As a gas for generating microbubbles, nitrogen gas or the like can be formed into microdroplets in addition to ozone gas. The microbubble generation unit 30 can create oxygen-activated species necessary for resist destruction by pressurizing ozone gas into a nanovalve and allowing microbubbles to coexist in sulfuric acid.

  In addition, when pure water is sprayed from the cleaning water supply unit 19 </ b> M to the substrate W and the substrate W is cleaned, waste liquid other than sulfuric acid can be discharged to the tank 62 through the pipe 60.

  As described above, an oxidizing gas such as ozone gas is made into microbubbles and contained in a resist stripping solution such as sulfuric acid to produce a resist stripping solution containing microbubbles. The resist is peeled off from the substrate W. Since the conventionally used hydrogen peroxide solution is not used, the resist stripping solution such as sulfuric acid is not diluted with the hydrogen peroxide solution, and the resist stripping process can be performed efficiently.

  In the case of conventional resist stripping using sulfuric acid and hydrogen peroxide solution, the following chemical reaction formula is obtained.

H ₂ SO ₄ + H ₂ O ₂ → H ₂ SO ₅ + H ₂ O
C _X H _Y O _X (resist) + H ₂ SO ₅ → CO ₂ + H ₂ O + H ₂ SO ₄
On the other hand, in the case of resist stripping using sulfuric acid and ozone gas without using hydrogen peroxide, the following chemical reaction formula is obtained.

H ₂ SO ₄ + O ₃ → H ₂ SO ₅ + O ₂
C _X H _Y O _X (resist) + H ₂ SO ₅ → CO ₂ + H ₂ O + H ₂ SO ₄
That is, compared with the case of using conventional sulfuric acid and hydrogen peroxide solution, by using sulfuric acid and ozone gas as in the embodiment of the present invention, the same or equivalent resist effect can be exhibited.

The microbubble generation unit 30 can stably contain microbubbles of an oxidizing gas such as ozone gas in a resist stripping solution such as sulfuric acid, and can control the resist stripping property to be constant.
A resist stripping solution such as sulfuric acid is not used as an oxidizing species, the resist stripping process can be performed efficiently, and a resist stripping solution such as sulfuric acid can be reused. Thereby, an environmental load can be reduced.

  Furthermore, since the resist stripping solution in which microbubbles are stably generated can perform the resist stripping process on the substrate W, the uniformity of the resist stripping process can be improved. For this reason, the resist stripping processing time can be shortened.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG.

  A single wafer processing unit 4B of the substrate processing apparatus shown in FIG. 4 includes a resist stripping apparatus 10B, a substrate holding unit 11B, an operation unit 12B, a cup 14B, and a supply nozzle 15B as an example of a supply unit.

  The substrate holding part 11B includes a disk spin table 17B, a rotating shaft 18B, and a motor 19B. A substrate W is detachably fixed on the spin table 17B. A spin table 17B is fixed to the tip of the rotating shaft 18B. As the motor 19B operates according to a command from the control unit 20B, the spin table 17B can continuously rotate in the R direction.

The supply nozzle 15B shown in FIG. 4 is disposed above the substrate W, and when the operation unit 12B is operated according to a command from the control unit 20B , the swing arm 80 of the supply nozzle 15B moves in the Z direction (vertical direction) and the X direction. It can move in the radial direction of the substrate W.

  Next, the resist stripping apparatus 10B shown in FIG. 4 will be described.

  The resist stripping apparatus 10B shown in FIG. 4 includes a microbubble generation unit 30B, an ozone gas bubbling unit 32B, an infuser 85, a pump 86, and an ozone gas supply unit 87. The microbubble generation unit 30 </ b> B is connected to the pump 86 and the infuser 85 via a pipe 88. The piping 89 of the ozone gas bubbling portion 32B reaches the microbubble generation unit 30B. The piping 90 of the supply nozzle 15B also reaches the inside of the microbubble generation unit 30B.

When the control unit 20 </ b> B operates the pump 86 , the sulfuric acid 91 in the microbubble generating unit 30 </ b> B is circulated through the pipe 88 and is heated by the infuser 85. The ozone gas bubbling unit 32B generates a large number of microbubbles of ozone gas and mixes them with the sulfuric acid 91 in the microbubble generating unit 30B through the pipe 89.

The sulfuric acid 91 containing minute bubbles is ejected from the supply nozzle 15 </ b> B to the substrate W through the pipe 90 to form droplets, whereby the resist of the substrate W can be removed. At this time, ozone gas 92 is supplied from the ozone gas supply unit 87.

  Thus, ozone gas microbubbles from the ozone gas bubbling section 32B are dissolved in sulfuric acid 91, and sulfuric acid 91 containing ozone gas microbubbles, and preferably ozone gas 92 from the ozone gas supply section 87 is supplied to the supply nozzle 15B as a mixed spray. Are mixed on the substrate W.

As shown in FIG. 4, after sulfuric acid 91 containing fine bubbles of ozone gas is sprayed from the supply nozzle 15B onto the substrate W and the resist of the substrate W is removed, the used sulfuric acid drainage enters the tank 65 and enters the light source 67. and when passing between the light sensor 68 is detected concentration of sulfuric acid. Based on the detection result of the concentration of sulfuric acid, the control unit 20B determines whether or not sulfuric acid can be used again. If the sulfuric acid can be used again, the control unit 20B operates the pump 45 to supply sulfuric acid. When the sulfuric acid cannot be reused, the valve 66 is opened and the sulfuric acid is discharged into the tank 70.

Thereby, the sulfuric acid 91 containing microbubbles can be reused, the resist stripping solution such as sulfuric acid can be prevented from being diluted, the resist stripping solution can be reused, and the resist stripping process can be efficiently performed. it can.
The substrate processing apparatus of the present invention is a substrate processing apparatus for supplying a resist stripping solution to the surface of a substrate and stripping the resist from the substrate, wherein microbubbles of an oxidizing gas are mixed in the resist stripping solution to remove the microbubbles. A microbubble generating unit that generates a resist stripping solution including the supply, and a supply unit that supplies the resist stripping solution containing microbubbles from the microbubble generating unit to the surface of the substrate. Thereby, it is possible to prevent the resist stripping solution such as sulfuric acid from being diluted and to reuse the resist stripping solution, so that the resist stripping can be performed efficiently.

  The supply unit is a supply nozzle disposed on the substrate. Thereby, the resist stripping solution containing minute bubbles can be reliably supplied onto the substrate from the supply nozzle to perform the resist stripping process.

  The resist stripping solution containing microbubbles is supplied as droplets from the supply nozzle to the surface of the substrate. Thereby, the resist stripping solution can reliably strip the resist on the substrate.

  When the resist stripping solution containing microbubbles is made into droplets, an oxidizing gas is further supplied to the resist stripping solution. Thereby, the resist stripping solution can strip the resist of the substrate more reliably.

A resist stripping solution containing heated microbubbles is used. Thereby, the oxidizing gas can efficiently remove the resist, and the resist peelability can be improved.

  By passing an oxidizing gas through the porous film to generate microbubbles and releasing the microbubbles into the resist stripping solution, a resist stripping solution containing microbubbles is generated. Thereby, the resist stripping solution containing microbubbles can reliably strip the resist on the substrate.

  By the way, in the present invention, microbubbles are also called microbubbles or micro / nano bubbles, and are a concept including micro bubbles (MB), micro nano bubbles (MNB), and nano bubbles (NB). Microbubbles (MB) refer to microbubbles having a bubble diameter of 10 μm to several tens of μm or less when they are generated, and micronanobubble (MNB) is a bubble diameter of several hundred nm to 10 μm at the time of generation. It refers to the following minute bubbles. Furthermore, nanobubbles (NB) refer to minute bubbles of several hundred nm or less.

  Furthermore, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiments of the present invention. For example, you may delete some components from all the components shown by embodiment of this invention. Furthermore, you may combine the component covering different embodiment suitably.

1 is a diagram illustrating a first preferred embodiment of a substrate processing apparatus of the present invention. It is a figure which shows the processing unit shown in FIG. It is a figure which shows the structural example of a microbubble production | generation unit. It is a figure which shows 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate processing apparatus 4 Processing unit 10 Resist peeling apparatus 15 Supply nozzle which is an example of supply part 30 Microbubble production | generation unit 32 Ozone gas supply part (oxidizing gas supply part)
32,53 Ozone gas supply unit (oxidizing gas supply unit)
51 1st heater 52 2nd heater 34 Sulfuric acid supply part (resist stripping liquid supply part)
40 Sulfuric acid containing microbubbles (resist stripping solution containing microbubbles)
W substrate

Claims (3)

A substrate processing apparatus for stripping a resist from the substrate by supplying sulfuric acid as a resist stripping solution to the surface of the substrate,
A microbubble generating unit that mixes microbubbles of ozone gas in the resist stripper to generate a resist stripper containing the microbubbles;
A supply nozzle disposed on the substrate and supplying a resist stripping solution containing the microbubbles from the microbubble generating unit in the form of droplets on the surface of the substrate;
When making the resist stripping solution containing microbubbles into droplets, an ozone gas supply unit that further supplies ozone gas to the resist stripping solution containing microbubbles,
Piping for returning the resist stripping solution supplied to the surface of the substrate to the microbubble generating unit ;
A pump provided in the middle of this pipe,
A sensor for detecting a sulfuric acid concentration of the resist stripping solution after being supplied to the surface of the substrate;
Based on the detection result of this sensor, and having a control unit that determines whether or not the stripping liquid after being supplied to the surface of the substrate can be reused,
When it is determined that the stripping liquid after being supplied to the surface of the substrate can be reused based on the detection signal of the sensor, the control unit activates the pump and supplies it to the surface of the substrate. The substrate processing apparatus is characterized in that the stripping solution after being returned to the microbubble generating unit via the pipe . Resist stripping solution substrate processing apparatus according to claim 1, wherein a is used which includes a heated the resist stripping solution or heated the microbubbles. A substrate processing method for removing sulfuric acid from the surface of the substrate by supplying sulfuric acid as a resist stripping solution to the surface of the substrate,
A step of mixing a microbubble of ozone gas into the sulfuric acid using a microbubble generating unit to generate a resist stripping solution containing the microbubble;
Supplying the resist stripping solution containing the microbubbles to the surface of the substrate by making it into droplets using ozone gas;
Detecting the sulfuric acid concentration of the resist stripping solution after being supplied to the surface of the substrate;
Based on the sulfuric acid concentration detected in the step of detecting the sulfuric acid concentration, determining whether the resist stripping solution after being supplied to the surface of the substrate is reusable,
A step of returning the resist stripping liquid after being supplied to the surface of the substrate to the fine bubble generating unit when it is determined that it can be reused in the step of determining ;
A substrate processing method comprising:

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